The present invention relates to a bendable portion of an endoscope, using a bending mechanism to allow directional control of observation through the endoscope.
In general, a flexible endoscope useful for surgical procedures is provided with an insert tube, a bendable portion at the insertion end of the insert tube, and a control portion accessible to the operator.
Japanese Laid-open Patent Publication No. HEI 5-15485 discloses a bending mechanism for a bendable endoscope portion that uses a flat elastic sheet having a pressure chamber for bending the bendable portion. An operator controls a pumping mechanism to pump fluid into and out of the pressure chamber to expand and deflate the elastic sheet. Deformation of the elastic sheet in both vertical and lateral directions bends the bendable portion. However, since the diameter of the bendable portion changes when the elastic sheet deforms, it is difficult to make a slender bendable portion with this technique. Furthermore the bending mechanism disclosed in the above-mentioned publication cannot bend the bendable portion to a large angle relative to its own length.